On 21 March 2017 at 01:44, Jason Merrill <ja...@redhat.com> wrote:
>> It looks strange to me. Why not change the definition of check_new instead
>> of changing the condition that uses it?
>
> Agreed. Also, let's factor the new tests out into a function, say
> non_allocating_fn_p.
This also conveniently let's me provide a ChangeLog that reads like a
Real Front-End
Developer would've written it. :) New tests re-tested on Linux-x64,
running full suite
on Linux-PPC64.
2017-03-21 Ville Voutilainen <ville.voutilai...@gmail.com>
gcc/
PR c++/35878
* cp/init.c (non_allocating_fn_p): New.
(build_new_1): Call it.
testsuite/
PR c++/35878
* g++.dg/init/pr35878_1.C: New.
* g++.dg/init/pr35878_2.C: Likewise.
* g++.dg/init/pr35878_3.C: Likewise.
diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 8bfcbde..dc5a5f7 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -2693,6 +2693,21 @@ malloc_alignment ()
return MAX (max_align_t_align(), MALLOC_ABI_ALIGNMENT);
}
+/* Determine whether an allocation function is a namespace-scope
+ non-replaceable placement new function. See DR 1748.
+ TODO: Enable in all standard modes. */
+static bool non_allocating_fn_p (tree alloc_fn)
+{
+ if ((cxx_dialect > cxx14) && DECL_NAMESPACE_SCOPE_P (alloc_fn))
+ {
+ tree first_arg = TREE_CHAIN (TYPE_ARG_TYPES (TREE_TYPE (alloc_fn)));
+ if ((TREE_VALUE (first_arg) == ptr_type_node)
+ && TREE_CHAIN (first_arg) == void_list_node)
+ return false;
+ }
+ return true;
+}
+
/* Generate code for a new-expression, including calling the "operator
new" function, initializing the object, and, if an exception occurs
during construction, cleaning up. The arguments are as for
@@ -3171,7 +3186,8 @@ build_new_1 (vec<tree, va_gc> **placement, tree type,
tree nelts,
So check for a null exception spec on the op new we just called. */
nothrow = TYPE_NOTHROW_P (TREE_TYPE (alloc_fn));
- check_new = (flag_check_new || nothrow);
+ check_new = flag_check_new
+ || (nothrow && non_allocating_fn_p (alloc_fn));
if (cookie_size)
{
diff --git a/gcc/testsuite/g++.dg/init/pr35878_1.C
b/gcc/testsuite/g++.dg/init/pr35878_1.C
new file mode 100644
index 0000000..b45c009
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/pr35878_1.C
@@ -0,0 +1,21 @@
+// { dg-options "-O2 --std=gnu++11" }
+// { dg-do compile }
+// { dg-final { scan-assembler "test.*%rdi, %rdi" { target i?86-*-* x86_64-*-*
} } }
+#include <new>
+#include <utility>
+
+struct s1{
+ int a;
+ int b;
+ int c;
+};
+
+void f1 (s1 * v, s1&& s)
+{
+ new (v) s1(std::move(s));
+}
+
+void f2 (s1 * v, s1&& s)
+{
+ *v = std::move(s);
+}
diff --git a/gcc/testsuite/g++.dg/init/pr35878_2.C
b/gcc/testsuite/g++.dg/init/pr35878_2.C
new file mode 100644
index 0000000..0664494
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/pr35878_2.C
@@ -0,0 +1,21 @@
+// { dg-options "-O2 --std=gnu++17 -fcheck-new" }
+// { dg-do compile }
+// { dg-final { scan-assembler "test.*%rdi, %rdi" { target i?86-*-* x86_64-*-*
} } }
+#include <new>
+#include <utility>
+
+struct s1{
+ int a;
+ int b;
+ int c;
+};
+
+void f1 (s1 * v, s1&& s)
+{
+ new (v) s1(std::move(s));
+}
+
+void f2 (s1 * v, s1&& s)
+{
+ *v = std::move(s);
+}
diff --git a/gcc/testsuite/g++.dg/init/pr35878_3.C
b/gcc/testsuite/g++.dg/init/pr35878_3.C
new file mode 100644
index 0000000..8a5614f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/pr35878_3.C
@@ -0,0 +1,21 @@
+// { dg-options "-O2 --std=gnu++17" }
+// { dg-do compile }
+// { dg-final { scan-assembler-not "test.*%rdi, %rdi" { target i?86-*-*
x86_64-*-* } } }
+#include <new>
+#include <utility>
+
+struct s1{
+ int a;
+ int b;
+ int c;
+};
+
+void f1 (s1 * v, s1&& s)
+{
+ new (v) s1(std::move(s));
+}
+
+void f2 (s1 * v, s1&& s)
+{
+ *v = std::move(s);
+}
